You can learn a whole bunch and pretty much teach yourself by playing with
SimSmith. I use it extensively. It's free and can be accessed at the
following URL. It also offers some excellent tutorials, but one must first
understand and internalize what a complex impedance truly represents.
Tutorials:
Download:
RFCAFE.com also offers a wealth of good information on the subject in
addition to all things RF.
Dave - W?LEV
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On Mon, Mar 30, 2020 at 6:26 PM Jerry Gaffke via Groups.Io <jgaffke=
[email protected]> wrote:
Paul,
I got it that you had some familiarity with Smith Charts, and were just
stumped on
why the tutorial was incomplete in identifying the frequencies involved.
I wrote the explanation such that others in the forum could also figure it
out.
I'm in about the same boat as you.
Slept through EE classes on using the Smith Chart some 45 years ago,
made a career in digital design. Now getting back to my ham radio roots.
It took a few weeks of going over material on the web to get comfortable
with Smith Charts.
I don't feel I have touched bottom unless I can perform the computations.
Python is an excellent choice, complex numbers are implemented in the core
language.
For example, in Jeff's tutorial
his first example using numbers can be summarized as follows:
Gamma = (Zload - Zo) / (Zload + Zo); If Zload = 50 + j200, then
Gamma = 0.8 + j0.4
Here's a complete python session to duplicate that computation:
def Gamma(Zload, Zo):
... return((Zload - Zo)/(Zload + Zo))
...
Gamma(50+200j, 50)
(0.8+0.4j)
The above example will run the same under Python 3.x as it does under 2.x
Both will give an answer of (0.8 + 0.4j)
But I recommend you stick with Python 3.x, as 2.x is now ancient history.
I'm thinking of someday creating a Python exercise to do the math
(including the plots)
of Jeff's tutorial. Start it out with an introduction to exactly what
complex numbers are.
I agree, a good explanation written for somebody starting from scratch
on such a "complex" subject matter as Smith Charts is not easy to cook up.
But writing it is a good exercise, you soon realize there are nooks and
crannies
of the subject you haven't quite figured out as well as you thought.
Jerry, KE7ER
On Mon, Mar 30, 2020 at 09:42 AM, Nbridgema wrote:
Jerry, thanks; it was enough to point out that I really hadn't missed
some
piece of information. I understand what you pointed out although I hadn't
followed it through as thoroughly as you. You were hearing my
frustration of
not being able to follow the statement verbatim.
Now retired, I've been re-engaging with RF electronics, which was a
childhood
fantasy. So I've been looking for tutorials on any number of subjects,
like
the Smith chart (as a refresher), and Python (about which I know less
than
zero, and lack any programming knowledge).
I observe a common denominator: the one skilled in a subject forgets how
much
they already know that will be required of the listener to understand
their
explanation. And I can't throw stones!! I now know I must have done the
same
thing explaining some aspect of propagation in optical fiber, and saw the
listener's eyes glaze over!
-Paul
I_B_Nbridgema
--
*Dave - W?LEV*
*Just Let Darwin Work*
*Just Think*
